In a large saucepan, place the crab on its back and cover with cold water. Cover and bring the pan to a simmer over low heat, and cook for 4 minutes. Remove from heat and let sit, covered, for 10 minutes.

Break off the crab legs and set aside. Pull off the large back shell, and clean out the debris. Remove the air sacs and break the body into small pieces. Crack the legs and claws, remove the meat, and set aside.

In a large wide pan, heat the olive oil and add the garlic. Cook for 5 minutes, then add the tomatoes and salt and pepper, to taste. Cook over medium-low heat for 20 minutes, then add the parsley and crabmeat. Simmer 5 minutes.

Bring 6 quarts of water to a boil over high heat and add 2 tablespoons salt. Cook the pasta in the water until it is tender yet al dente. Drain the pasta and add to the hot sauce. Toss over high heat for 1 minute, then divide evenly among 4 warmed pasta bowls and serve immediately.